New England Daily Snow

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More rain on the way

Summary

Another rain storm is likely on Wednesday with a period of upslope snow to follow on Thursday. The storm track continues to favor warmer storms through the weekend. A pattern change may be on the horizon, but not likely until mid December.

Short Term Forecast

Sunshine prevailed through midday across New England on Sunday with high clouds moving in after lunch and rain for most by dinner. Snow conditions remained pretty good on Sunday (see above), albeit soft with temperatures in the mid 40s at bases and above freezing on the slopes. It's a bit early yet to see what snow conditions are on Monday morning following the ~0.75" of rain that fell between ~4PM and midnight. My guess is that the machine made snows drained the rain fairly well and resorts lost some coverage on the fringes. First light might show some ponding, slop, and mud on the cams. 

Radar analysis on Monday morning ending at 5:15AM. 

Rain contains to move out of Maine on early on Monday morning with snow falling across far northern regions. Temperatures have dropped back into the 30s across Northern Vermont and cold air will continue to filter down through New England on Monday. An early round of upslope rain and snow showers through noon is not out of the question as the upper-level trough -- currently crossing the St. Lawrence River valley -- clears the region. We're unfortunately not going to see much if any accumulation. We have 0-1" forecasts on Monday for Jay, Sugarbush, Stowe, Smuggs, Cannon, and Tuckerman.

GFS model forecast for 4AM to 10PM Wednesday

Our next shot at precipitation arrives on Wednesday as a storm moves to our west and north across southern Canada. This storm is going to initially produce rain and it should go over to snow across the mountains overnight into Thursday. Here are some of the details:

  • Rain starts from west to east around noon on Wednesday and continues into the evening. Rainfall totals of 0.5 to 1.5" are likely with max totals in the Whites exposed to southerly upslope flow.
  • Winds will crank out of the south-southwest on Wednesday afternoon 30-50 mph and then go over to potentially stronger west-northwest winds late evening.
  • Temperatures (and dewpoint temperatures) on Tuesday will push through the 40s with the rain and then decrease back below freezing on Wednesday night.
  • Rain changes over to a period of snow following the cold frontal passage late Wednesday evening. How much moisture remains as temperatures crash is unclear, but a few inches of snow in the mountains Wednesday night is likely.
  • Impacts: Some coverage and depth losses are likely with another round of heavy rain, warm temperatures likely producing widespread fog, and strong south winds on Wednesday. The sharp decrease in temperatures may produce hardening of the underlying snowpack with some ice/crusty conditions possible.

 

GFS model forecast for 1AM to 4PM Thursday. 

West-northwest winds will usher in colder air and lead to persistent upslope flow on Thursday. The airmass looks to tap some Great Lakes moisture and should lead to a solid round of upslope snows across the Greens and northern Whites during the day on Thursday. Snow showers should be confined to the mountains, but there is a shot at some snow squalls midday through the foothills.

 

Multi-model comparison of 24-hour snowfall ending at 1PM on Thursday. 

I'm fairly impressed by the different model solutions and the uncertainty in how much snow actually falls in the 24-hour period from 1PM on Wednesday through 1PM on Thursday. This period covers the change-over to snow following the frontal passage and onset of upslope flows (with lake-effect) on Thursday. There is a clear signal for enhanced totals >6" across the western Adirondacks with the lake-effect snow and then a signal for snow >3" across the high terrain in the Whites. Otherwise, there are different solutions as to how much snow falls in the Greens through Vermont and lower elevations (mid-slopes) in New Hampshire. Clearly totals >3" are possible, but not a lock.

OpenSnow 5-day snowfall total forecast through Friday.

Our OpenSnow forecast includes the more robust GFS model solution and pumps out 2-4" at Jay, 4-6" at Killington, and 2-4" at Sugarloaf to give you an idea of the spread. Combined with some 0-1" totals in the forecast from Monday and again on Friday, forecast totals are anywhere from 2-11" across the region. Take out of the GFS model and you end up with some slightly lower totals. If I were a betting man, I might take the under on these totals, especially after looking at the ECMWF model ensemble odds for >3" of snow below:

Extended Forecast

ECMWF model forecast for the U.S. from 1AM on Saturday through 1PM on Sunday. Note the storm cross the northern tier of the Great Lakes heading into Canada.

The storm track continue to favor storms moving to our north and west over the Great Lakes region through (at least) the weekend. As a result, high pressure will be fleeting on Friday and early Saturday ahead of our next shot at rain on Saturday night with, once again, a brief shot at upslope snows on Sunday.

ECMWF ensemble model forecast for 24-hour snowfall in central Vermont. 

The ECMWF ensemble grid for 24-hour snowfall in central Vermont demonstrates at least some snow is possible with the storm over the weekend, but note (1) that gray shading above is less than 2" and (2) odds are less than 15-20%. The ensemble grid doesn't start suggesting higher snowfalls likely until next week after 12/6 and even those solutions are sporadic from ensemble member to ensemble member.

Upper-level flow and departure from climatology (anomaly) for 3-8 December from the ECMWF ensemble. 

The long-range forecast is hinting at some changes for the Northeast that will hopefully signify and end to the more westerly storm track through the Great Lakes. The image above is a 5-day forecast for the period from 3-8 December still showing generally zonal (mostly west-to-east) flow across the U.S. What is interesting about this forecast is the pair of ridges setting up in high latitudes over Alaska and Greenland. The one over Greenland is pretty stationary, a block, that will hopeful gum everything up over North America. As a result, we could see that trough of colder air over Canada drop into the U.S. and lead to storm development over the eastern U.S. In any case, it should lead to more meridional (south-to-north) flow and increase the odds for bigger and colder storms into the second week of December. Maybe?

The New England Daily Snow will update on Wednesday to round out November.

-Dr. Jay